Ringing arrangement por four-wire circuits



C. S. DEMAREST.

RINGING AR'RANGEMENT FOR FOUR-WIRE CIRCUITS,

APPLICATION FILED DEC. 2. mu.

1 3 1 7, 1 55 Patented Sept. 30, 1919.

IN V EN TOR.

ATTORNEY UNITED STATES PATENT OFFICE.

CHARLES S. DEMAREST, OF BROOKLYN, NEW YORK, ASSIGNOR TO AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

RINGING- ARRANGEMENT FOR. FOUR-WIRE CIRCUITS.

Application filed December 2, 1918. Serial No. 265,037.

'- To all whom it may concern:

Be it known that I, CHARLES S. DEMAnns'r, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Ringing Arrangements for Four-Wire Circuits, of which the following is a specification.

This invention relates to transmission circuits and more particularly to transmission circuits of the type known as four wire circuits.

The principal feature of this invention consists in an arrangement at the junction point of a two wire system and a four wire system whereby a ringing current of a definite frequency incoming from either system may be relayed to the other system. This result is accomplished by providing a ringing responsive relay in each of the one-way paths comprising the four wire circuit at the junction point of the four wire circuit and the two wire circuit in such a manner that both relays will respond to incoming signaling current from the two wire circuit to switch a local source of signaling current to the outgoing path of the four wire circuit while but one relay responds to signaling current incoming from the four wire circuit andfunctions to apply the relayed source of signaling current to the two wire circuit.

One of the relays is renderdd unresponsive to signaling current incoming from one path of the four wire system by reason of the fact that the two wire circuit is balsystem as is necessary to an understanding of the invention.

Referring to the drawing a' four wire circuit is shown comprising two wire lines L and 'L for. transmission in opposite directions said two wire lines being associated with the terminating two wire circuit L rangement for a terminating two wire line is provided. The two paths L and L of the four wire circuit may be provided with one-way repeaters at suitable intervals along the line in order to provide the desired gain in transmission. The apparatus so far described is of the general type illustrated in the application of George A. Campbell, Serial Number 72,606, filed January 17, 1916, and a full illustration of the theory and operation of a four wire circuit may be had by reference to said application.

In order to relay ringing current in accordance with this invention two ringing responsive relays 2 and 3 are provided, the former being associated with the path L and the latter being associated with the path L The line L 1s balanced with respect to the incomin path L by means of an artificial line N so that the relay 3 is unresponsive to current transmitted from the path L Both relays2 and 3 are responsive I the four wire circuit. ;The relay 2 responds to ringing current of this frequency incoming from the path L to apply the source 4 to the two wire line L. In order to prevent anunbalance of the system due to the fact that the line L is disconnected from the junction during this operation means is rovided whereby an auxiliary net work is substituted for the line L. This prevents the relay 3 from being actuated by ringing current from the path L which might be impressed upon said relay due to the unbalanced condition of the circuit with respect to the artificial line N.-

The operation is as follows: Signaling current incoming from the line L flows over conductors 5 to points 6 and 7 where the current divides part flowing through the bridge circuit including the autotransformer 8 to actuate the relay 2. The current flowing over conductors 5 and in series throu h the transformer 1 acts only to actuate the Patented Sept. 30, 1919.

moves a short circuit about the winding ringing responsive relay 3. Relay upon I being energized opens the circuit of a norrelay 10. Relay 9 upon being deenergized ate alternating current of the desire completes a circuit for the relay 11 which sets the generator 4: into operation to erfierrequency, which in practice may be in the neighborhood of 133 cycles. being deenergized also completes a circuit from ground over its back contact and through the winding of relay 10 to battery.

Relay 10 closes a circuit from ground over' the back contact of relay 9 front contact of relay 10 through the winding of relay 12 to battery. Relay 12 disconnects the path L from the circuit 13 and connects 1tto conductors 14 leading to the generator 4 so that ringing current from said generator is applied to the path L and transmitted over one side of the four wire system to the distant station.

Ringing current transmitted from the distant station over the path L actuates the relay 2 but owing to the fact that the incoming conductors 15 from said path .are

.bridged across equal potential points 6 and 7 with respect to the artificial line N and the two wire line L the energy applied to points-6 and 7 divides substantiallyequally etween the line L and the artificial line N and'as a result no efi'ect is produced upon the relay 3. The relay 2 upon being energized again opens the circuit of relay 9 which at its back contact completes the circuit of relay 11 to set the generator 4- into operation. Since the relay 3 is not actuated the winding of relay "10 is short circuited so that said relay is not actuated. Consequently relay 9 upon being deenerv.gized completes a circuit from ground over its back contact, over the back contact of relay 10 and through the windings of relays 1t; and 17 in parallel to battery. Relay 16 disconnects the two-wire line L from the said source is transmitte balance were not maintained a portion. of

the energy incoming from conductors 15 7 would be transmitted to the relay 3 to cause a false operation thereof.

It will be seen that by means of the above arrangement ringing current may be relayed from one system to another in either direction by placing the relaying apparatus under the joint'control of two ringing responsive relays one, of which responds only 66 to current incoming from one system and Relay 9 upon m me. I

the other of'whichresponds to, current incoming from either system. It will also be p:

obvious that the general rinciples herein disclosed may be embodied in many other organizations widely different from those illustrated vwithout departing from the spirit of invention as defined in the following claims.

What is claimed is: i

1. In a signaling system, a four wire transmission circuit, a two Wire transmission circuit, means interconnecting said circuits,

a relay responsive to signaling current transmltted from one of said circuits only, a second relay responsive to slgnali'ng currents transmitted from eithermircuit, means responsive to the energization of one of said relays to apply signaling current to one of said circuits, and means responsive to the energization of both" of said relays to apply signaling current'to the other circuit.

2. In a signaling system, a transmission circuit comprising two paths, one for transmitting in one direction and the other for transmitting in the opposite direction, a second transmission circuit comprising a single path for transmitting in either direction, means interconnecting said circuits, a relay responsive to signaling currents transmitted from one of said circuits only, a

second relay responsive to signaling cur rents transmitted from either circuit, means responsive to the energization of one of said relays to apply signaling current to one of said circuits, and means responsive to the energization of both of said relays to apply signaling current to the other circuit.

3. In a signaling system, a transmission circuit comprising two paths, one for trans-' mitting in one direction and the other for transmitting in the opposite direction, a second transmission circuit comprising a single path for transmitting in either direction, means interconnecting said circuits, a relay responsive, to signaling currents incoming from either circuit, a second relay responsive to signaling currents incoming from one of said circuits only, means responsive to the energization of said relay to apply signaling current to the othercircuit, and means responslve to the energization of the other relay to apply signaling current to the rema1n1ng circuit.

4. In a signaling system, a transmission circuit comprising two .paths, one for transmitting in one direction and the other for transmitting in the opposite direction, a second transmission circuit comprising a single path for transmitting in either direction, means interconnecting said circuits, a relay responsive to signaling currents incoming from said second mentioned circuit only, a second relay responsive to signaling currents incoming from either circuit, means responsiveto the energization of both said relays to apply signalin current to said first mentioned circuit, and means responsive to the energization of said first mentioned relay alone to apply signaling current to said second mentioned circuit.

5. In a signaling system, a transmission circuit comprising two paths, one for transmitting in one direction and the other for transmitting in the opposite direction, a second transmlssion circuit comprising a single path for transmitting in either direction, means interconnecting said circuits, a pair of relays associated with said circuits and responsive to signaling currents transmitted thereover, means responsive to the energization of both of said relays to apply signaling currents to one of said circuits, and means responsive to the energization of one of said relays alone to apply signaling current to the other of said circuits.

6. In a signaling system, a transmission circuit comprising two paths, One for transmitting in one direction and the other for transmitting in the opposite direction, a second transmission circuit comprising a single path for transmitting in either direction, means interconnecting said circuits, a pair of relays associated with said circuits and responsive to signaling currents transmitted thereover, means responsive to the energization of both of said relays to apply signaling current to said first mentioned circuit, and means responsive to the energization of one of said relays alone to apply signaling current to saidsecond mentionedcircuit.

7. In a signaling system, a transmission circuit comprising two paths one for transmitting in one direction and the other for transmitting in the opposite direction, a second transmission circuit comprising a single path for transmitting in either direction, means interconnecting said circuits, means responsive to signaling current of a definite frequency incoming from one of said circuits to apply current of that frequency to the other circuit, and means responsive to signaling current of the same frequency incoming from the latter circuit to apply signaling current of that frequency to the first circuit.

8. A transmission circuit comprising a path for transmitting in either direction, an artificial line for balancing said path, a second transmission circuit comprising a path for transmitting in one direction connected to equi-potcntial points between said first circuit and said artificial line and a path for transmitting in the opposite direction inductively related to said first mentioned path and artificial line, a ringing responsive relay associated with each of said second and third mentioned paths, both of said relays responding to ringing current incoming over said first mentioned path to apply ringing current to one of the other two paths, and one only of said relays responding to ringing current incoming over the remaining path to apply ringing current to said first mentioned path.

9. In a signaling system, a transmission circuit comprising two-paths, one for trans mitting in one direction and the other for transmitting in the opposite direction, a second transmission circuit comprising a single path for transmitting in either direction, means interconnectin said circuits, means associated with one o the paths of said first mentioned circuit and responsive to incoming currents from said second circuit to relay signaling currents to said path, an artificial line for balancing said second circuit with respect to said means to prevent said means responding to incoming currents from the other path of said first mentioned circuit, means to disconnect said second circuit from said first circuit and apply signaling current thereto, and means functioning durin the latter operation to balance said artificial line with respect to said first mentioned means to revent its actuation.

In testimony whereof I have signed my name to this specification this twenty-ninth day of November, 1918.

CHARLES S. DEMAREST. 

